HgCdTe长波光伏探测器的表面漏电流及1/f噪声研究  

Analysis of surface leakage and 1/f noise on long-wavelength infrared HgCdTe photodiodes

作　　者：孙涛[1] 陈兴国[1] 胡晓宁[1] 李言谨[1] 

机构地区：[1]中国科学院上海技术物理所功能材料器件中心,上海200083

出　　处：《物理学报》2005年第7期3357-3362,共6页Acta Physica Sinica

摘　　要：在同一Hg1-xCdxTe晶片上(x=0.217)制备了单层ZnS钝化和双层(CdTe+ZnS)钝化的两种器件,对器件烘烤前后的暗电流和1f噪声进行了测试,烘烤前发现,ZnS钝化的器件在反偏较大时具有较大的表面隧道电流,而这种表面漏电流是ZnS钝化器件具有较大1f噪声电流的原因,通过高分辨x射线衍射中的倒易点阵技术(reciprocal spacemapping,RSM)研究了单双层钝化对HgCdTe外延层晶格完整性的影响,发现单层ZnS钝化的HgCdTe外延层产生了大量缺陷,而这些缺陷正是ZnS钝化器件具有较大表面漏电流和1f噪声的原因.经过高温烘烤后,ZnS钝化的器件暗电流和1f噪声增加,而双层钝化器件经过高温烘烤后性能提高.RSM的研究表明,高温烘烤后ZnS钝化的HgCdTe外延层产生大量缺陷,这些缺陷正是单层钝化器件表面漏电流和1f噪声电流增加的原因.The long-wavelength infrared Hg1-x Cd-x Te photovoltaic detectors with x = 0.217 passivated by single ZnS layer and dual (CdTe + ZnS) layers were fabricated in the same wafer. The fabricated devices were characterized by measurements of dark currents and 1/f noise. The diode passivated by dual (CdTe + ZnS) layers showed a higher performance compared to the diode passivated by the single ZnS layer at high reverse bias, and modeling of diode dark current mechanisms indicated that the performance of the diode passivated by single ZnS was strongly affected by tunneling current related to the surface defects, which was responsible for the dark currents and 1/f noise characteristics. By the analysis of x-ray reciprocal space map (RSM), it was found that the Q(y) direction broadening of HgCdTe epitaxial layer passivated by ZnS was wider after passivation, which confirmed the existence of defects in the surface of HgCdTe epitaxial layer passivated by ZnS. In order to investigate the effect of surface passivation on the stability of two kinds of diodes, dark currents and 1/f noise of the diodes were measured after vacuum baking for 10 h at 80 degrees C. The dark current mechanisms indicated that the performance of the diode passivated by single ZnS was strongly affected by the surface defects. By the analysis of RSM, It was found that the Q(y) direction broadening of HgCdTe epitaxial layer passivated by ZnS was wider after high-temperature baking, which also confirmed the existence of defects in the surface of HgCdTe epitaxial layer passivated by ZnS after baking.

关 键 词：HGCDTE 表面漏电流 光伏探测器 噪声研究 高分辨X射线衍射 mapping 1/f噪声 长波 高温烘烤 噪声电流 ZnS space 1/f噪声 外延层 隧道电流 倒易点阵 暗电流 钝化 器件 缺陷 单层 原因 RSM 晶片 

分 类 号：TN209[电子电信—物理电子学]